Offshore vertical-axis wind turbine and associated systems and methods

ABSTRACT

An offshore wind turbine has a vertical-axis wind turbine (VAWT) mounted on a platform. The VAWT has a vertical rotor and curved blades coupled to a gearbox and an electric generator. The VAWT can fixedly extend from the platform or may be capable of reclining on the platform either manually or automatically. The platform can be composed of modular elements coupled together. Offshore, the platform can be semi-submersible with the VAWT extending out of the water and with a counterbalance extending below the platform. Alternatively, the platform can float on the water&#39;s surface and can have several arms that extend outwardly from the VAWT to increase the platform&#39;s footprint. To anchor the turbine offshore, anchoring systems can anchor the platform to the seabed while allowing the floating wind turbine to adjust passively or actively to changes in sea level due to tidal variations or storm swells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 12/208,395, filed 11 Sep. 2008, and claims priority to U.S.Provisional Appl. No. 60/972,099 filed 13 Sep. 2007 and to U.S.Provisional Appl. No. 61/019,117 filed 7 Jan. 2008, which are allincorporated herein by reference.

BACKGROUND

Wind turbines convert wind energy into electricity. The two main typesof wind turbines include the horizontal-axis wind turbines and thevertical-axis wind turbines. The two main types of horizontal-axis windturbines include the upwind horizontal-axis wind turbines (HAWT) havingrotating blades upwind of the tower and include the downwindhorizontal-axis wind turbines (HADT) having rotating blades downwind ofthe tower. The two main types of vertical axis wind turbines include onetype having rotating blades without lift generating surfaces and includethe Darreius-Type having rotating blades with lift generating airfoils(VAWT).

An upwind horizontal-axis wind turbine (HAWT) 10 without guy cables isshown in FIG. 1A, and a Darrieus-Type vertical-axis wind turbine (VAWT)20 with curved blades and without guy-cables is shown in FIG. 1B. TheDarrieus-type vertical axis wind turbine 20 can have curved blades asshown in FIG. 1B or can have straight blades as stated in the originalpatent of George Darrieus in 1929.

The HAWT 10 has a rotor 12 and blades 14 with lifting surfaces mountedon a horizontal-axis and directed upwind atop a tower 16. Wind energyincident to the blades 14 rotates the rotor 12, and a gearbox and othercomponents (not shown) coupled to the rotor 12 communicate the rotationto an electric generator (not shown) that converts the rotation toelectrical energy. To be effective, the blades 12 must be directedrelative to the direction of the wind. Therefore, the HAWT 10 typicallyhas a yaw mechanism (not shown) to allow the blades 14 to rotate aroundthe tower 16.

Because the blades 14 are upwind of the tower 16, they must be made ofrigid, strong material so they cannot be bent back by the wind and hitthe tower 16. Requiring more rigid materials, the blades 14 are moreexpensive to manufacture and are heavy. In addition, the tower's yawmechanism must be strong so it can determine the direction of the winddirection and orient the blades 14 into the direction of the wind.Finally, the tower 16 must also be strong so it can support the heavyrotor, gear-box, generator, and other equipment on top of the tower 16.Therefore, the tower 16 requires more materials, is more expensive tobuild, and is heavy.

Overall, the HAWT 10 as shown in FIG. 1A is a ‘rigid’ wind turbine,requires more materials, is heavy, and has a high center of gravity. Inaddition, it needs to be oriented to face the wind, and requires a firmfoundation or platform. Therefore, it is very expensive to build afloating platform to support the HAWT 10, which is heavy, has a highcenter of gravity, and requires a very stable platform.

By contrast, the VAWT 20 as shown in FIG. 1B has a rotor 22 that runsvertically from the ground and has curved blades 24 connected at therotor's ends. This vertical rotor 22 sits on a bearing and gearboxcomponent 26 and drives an electric generator 28. Unlike the HAWT 10,the VAWT 20 is omni-directional and does not need to be oriented intothe wind. In addition, the VAWT 20 has a low center of gravity with itsheavy components such a gearbox, generator, braking and control systempositioned near the ground. Therefore, the VAWT 20 does not require anas rigid rotor 22 as with the HAWT's tower (16; FIG. 1A) to supportthese components. Example of VAWTs in the prior art can be found in thewebsite of www.ecopowerusa.com.

The HAWTs 10 have been widely used in land-based windfarms around theworld. HAWTs have also been used in offshore windfarms in Europe. InFIG. 2A, for example, a first type of offshore HAWT 30A has theconventional components of a rotor 12 and blades 14 supportedhorizontally on a vertical tower 16. These conventional components reston a fixed support 32 rigidly affixed to the sea floor 40. Examples ofthe offshore HAWT 30A illustrated in FIG. 2A can be found in U.S. PatentApplication Publication 2007/0040388, published February 2007, and PCTPublished Application WO/03/004870, published Jan. 16, 2003.

In FIG. 2B, another type of offshore HAWT 30B also has the conventionalcomponents of rotor 12, blades 14, and tower 16, but these componentsrest on a floating support 34 that is rigidly affixed to the sea floor40 by cables 36. An example of the HAWT 30B illustrated in FIG. 2B canbe found in PCT Application Publication 2005/021961, published Mar. 10,2005. As these prior art publications disclose many well-knownimplementation details concerning the design and operation of windturbines generally, they are all incorporated herein by reference intheir entireties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a land-based upwind horizontal-axis wind turbine accordingto the prior art.

FIG. 1B shows a land-based vertical-axis wind turbine according to theprior art.

FIG. 2A shows an upwind horizontal-axis wind turbine according to theprior art having a fixed support offshore.

FIG. 2B shows an upwind horizontal-axis wind turbine according to theprior art having a floating support offshore.

FIGS. 3A-3B show side and top views of a first embodiment of an offshorewind turbine having a vertical-axis wind turbine and having acounterweight for deeper waters.

FIGS. 4A-4B show upper and lower perspective views of a secondembodiment of an offshore wind turbine for shallower waters.

FIGS. 5A-5B show top and cross-sectional views of an end of the floatingbarge's arm having a pulley system for raising or lowering the anchorwith winches (not shown).

FIGS. 6A-6B show upper and lower perspective views of a third embodimentof an offshore wind turbine.

FIG. 7A shows a perspective view of a fourth embodiment of an offshorewind turbine having a submersible floating platform.

FIG. 7B shows the offshore wind turbine of FIG. 7A with an alternativeform of attaching guy cables to the VAWT.

FIG. 7C shows a horizontal axis wind turbine on the submersible floatingplatform of FIG. 7A.

FIG. 7D shows a downwind horizontal axis wind turbine on the submersiblefloating platform of FIG. 7A.

FIGS. 8A-8C show steps to assemble the disclosed offshore wind turbineof FIG. 7A on the beach and deploy it into the sea.

FIGS. 9A-9B show side and top views of a fifth embodiment of an offshorewind turbine having extendable toes.

FIG. 10 shows a side view of a sixth embodiment of an offshore windturbine having reclining rotor and blades.

FIG. 11 is a top view showing a modular floating platform for use withthe disclosed offshore wind turbines.

FIG. 12 shows a cross-sectional view of floatation elements for themodular floating platform of FIG. 11.

FIGS. 13A-13C show steps to assemble the disclosed floating windturbines having portable anchors.

FIGS. 14A-14D show the anchoring system of FIGS. 4A-4B adjusting todifferent sea levels.

FIGS. 15A-15C show various passively adjustable anchoring systems forthe disclosed offshore wind turbines.

FIGS. 16A-16B show an actively adjustable anchoring system for thedisclosed offshore wind turbines.

FIGS. 17A-17B show a wind farm matrix having an arrangement of multipleoffshore wind turbines interconnected together at an offshore locationand connected to a land-based station.

FIG. 18 shows a wind farm matrix having an arrangement of multipleoffshore wind turbines interconnected together at an offshore locationand connected to a desalination system.

DETAILED DESCRIPTION

Embodiments of offshore wind turbines disclosed herein preferablycomprise vertical-axis wind turbines (VAWTs) mounted on platforms. TheVAWTs can be Darrieus-type with or without guy cables and can be mountedon floating or fixed platforms. The VAWT has a vertical rotor withcurved or straight blades coupled to a gearbox and an electricgenerator. Alternatively, the VAWT can have a direct-drive generatorwithout the gearbox. The vertical rotor can fixedly extend from thefloating or non-floating platform or may be tilted down to rest on theplatform either manually or automatically. The platform is preferablybuoyant so it can be floated to a desired destination offshore and towedback to the service beach for repairs and maintenance.

For deeper water, the platform can be a semi-submersible barge with theVAWT extending out of the water and with a counterbalance extendingbelow the platform to counterbalance the wind force against the windturbine. For shallower water that will not accommodate the verticalextent of a counter balance, the platform can float on the water'ssurface like a barge. Preferably, the barge is heavy and constructedwith low-cost reinforced concrete. To minimize the use of materials, thebarge is preferably not rectangular or circular shape and instead has across-shape or star-shape with three or more arms. For example, thebarge is preferably constructed with extended horizontal reaches tofasten guy cables, to counter-balance the wind force against the windturbine, and to keep the platform stable. In addition, to extend itshorizontal reaches, each of its arms can have a horizontal extender witha flotation tank at its end to increase stability.

For even shallower waters near shore, the VAWT on a floating platformcan be built with heavy but low-cost materials, such as reinforcedconcrete, and can be built and assembled on the beach, pushed into thesea, and towed to the site. By filling its flotation tanks with water,the floating platform can be lowered into the water to rest directlyonto the seabed, lake bed, or river bed. In this way, the platform canserve as a fixed platform or foundation for the VAWT during normaloperation, while the vertical rotor and blades of the VAWT extend abovethe water's surface. The platform can be re-floated by pumping the waterout of the flotation tanks so the VAWT and platform can be towed back tothe beach for repairs and maintenance. The ability to refloat theplatform and tow it for repairs can greatly reduce the cost of assembly,installation, repairs, and maintenance when compared to performing theseactivities at sea.

Various anchoring systems can be used for anchoring the platformsintended to float on or near the water's surface, including the catenaryanchoring system and the tension-leg anchoring system that are oftenused in the offshore industry for anchoring oil and gas drilling andproduction floating platforms. Some of these anchoring systems can haveweights and pulleys that anchor the platform to the seabed but allow thefloating wind turbine to adjust passively to changes in sea level due totidal variations or storm swells. In some embodiments, the anchoringsystems do not rigidly affix the platforms to the seabed, but insteadmerely rest on the seabed, which eases installation and removal of theVAWTs.

A. First Embodiment of Floating Wind Turbine Having Counterweight forDeeper Water

A first embodiment of an offshore wind turbine 100 illustrated in FIGS.3A-3B has a vertical-axis wind turbine (VAWT) 50 of the Darrieus type,although other types could be used. The VAWT 50 has a vertical rotor 52,a plurality of curved blades 54, a gearbox 56, an electric generator 58,and internal electrical components (not shown)—each of which can beessentially the same as those used with land-based VAWTs known in theart.

The offshore wind turbine 100 has a floating platform 110 that supportsthe VAWT 50 in the water. In general, the VAWT 50 mounted on thefloating platform 110 can be a cantilevered system or can be held upwith guy-cables. As shown, the floating platform 110 can be submergedbelow the surface of the water so that, under normal operatingconditions, the platform 110 can hold the VAWT's blades 52 above thewater level to catch the wind.

A central post 112 with a counterweight 114 extends below the platform110 to balance the turbine 100 and to keep the rotor 52 orientedrelatively vertically out of the water. This counterweight 114counterbalances against the moment of the wind force F over the windturbine 100 having height H that tends to tilt the wind turbine 100. Tominimize the tilting by the wind, the counterweight 114 having a weightW and extending a length L below the platform 110 should be designed insuch a way that W×L is at least greater than F×H.

The platform 110 can having either a hollow or a solid construction andcan be constructed using various materials. For example, the platform110 can be a shell made of composite, fiberglass, metal, concrete, orother material and can be filled with air or ballast material. Ingeneral, the floating platform 110 can be a barge or a semi-submersibleand can have extended horizontal reaches to increase its stability. Tominimize the use of material, for example, the platform 110 may not beof a rectangular or cylindrical shape and can instead have expandedhorizontal extents to increase its stability. In this way, the platform110 can have a cross or star-shape with 3 or more arms to providesupport in the water.

Although usable in various depths of water, this offshore wind turbine100 is suitable for use in deeper waters offshore having depths greaterthan 30 meters, for example. When deployed, the turbine's platform 110can be anchor to the seabed 40 using any number of available anchoringsystems known in the art. For example, the anchoring system can be acatenary anchoring system or a tension-leg anchoring system that is usedfor the floating platforms for offshore oil and gas drilling andproduction. As shown, a plurality of cables 116 and fasteners or mooringanchors 117 directly affix the platform 110 to the seabed 40 accordingto a taut leg mooring arrangement, but a catenary or other mooringarrangement could be used. In general, the cables 116 can be chain,steel wire rope, synthetic fiber rope, etc., and the fasteners ormooring anchors 117 can be drag embedded anchors, piles, suctionanchors, or any other type of mooring anchor known in the art. Thefloating platform 110 is anchored at three or more points to the seabedat three or points to prevent it from rotating. Details of differentanchoring systems that can be used with embodiments of the presentinvention are disclosed later herein.

The offshore wind turbine 100 does not suffer from some of the problemsassociated with offshore HAWTs known in the art. As discussedpreviously, offshore HAWTs must be oriented relative to wind directionand must be rigidly constructed and stabilized to support the rotor,blades, and tower above the water level. By contrast, the blades 54 ofthe VAWT 50 do not need to be oriented toward the wind's direction, andthe VAWT's rotor 52 and blades 54 can be constructed mainly ofcomposites or other lightweight, corrosion-resistant materials. Inaddition, the rotor 52 and blades 54 can be built with a low profileover the water so that the offshore wind turbine 100 can have a lowercenter of gravity—unlike offshore HAWTs that must support the heavyrotor, blades, gearbox, generator, and tower high above the water. Atthe height of 50 meters, for example, the wind over the sea may besignificantly greater than the wind over land, so the VAWT 50 on theoffshore wind turbine 100 can have greater energy output than itsland-based counterparts. In summary, the offshore wind turbine 100's lowcenter-of-gravity, omni-directional, and lightweight construction makeit easier to stabilize and support in the water with a low-cost floatingplatform.

B. Second Embodiment of Floating Wind Turbine Having a Platform withThree or More Extended Arms and a Portable Anchor

A second embodiment of an offshore wind turbine 200 is illustrated inFIGS. 4A-4B. As shown in FIG. 4A and similar to the previous embodiment,the offshore wind turbine 200 has a VAWT 50 with a rotor 52, curved orstraight lifting blades 54, a gearbox (not shown), an electric generator(not shown), or a direct-drive generator without a gearbox, and otherconventional components. In this embodiment, however, the rotor 52 andblades 54 extend from a stand 210 mounted on the surface of a floatingplatform or barge 220. This platform 220 can be made of heavy butlow-cost materials, such as reinforced concrete, to enhance itsstability over water. In addition, the platform 220 can have extendedhorizontal reaches, with three or more extended arms, to furtherincrease its stability as well as serving as a platform for theguy-cables to fasten to. (The stand 210 may house the gearbox, electricgenerator, or a direct-drive generator without the gearbox and otherconventional components). Guy cables 216 extend from the platform 220 tothe top of the rotor 52 to stabilize the assembly. By using these guycables 216, the rotor 52 and blades 54 can be made of lightweightmaterial and can mount close to the platform 220, giving the offshorewind turbine 200 a low profile and a low center of gravity.

The platform 220 is intended to float on the water's surface duringnormal operation, and the offshore wind turbine 200 may be deployed inoffshore regions of about 15 to 200 meters, for example. In general, theplatform 220 has a plurality of arms 222 arranged symmetrically aboutthe rotor 52, and in this implementation has three arms 222, althoughany number of arms could be used. The arms 222 gives the platform 220 arelatively large expanse while reducing the amount of material needed toconstruct the platform 220 if, for example, the platform 220 wereconstructed to have a square or circular footprint. Preferably, theexpanse of the platform 220 is at least 1.5 times the height of the VAWT50.

Not only does the platform 220 have a large expanse, the platform 220also preferably has a greater weight than the VAWT 50 that it supports.For example, the weight ratio between the platform 220 and the VAWT 50may be at least 50 to 1. In one implementation, the platform 220 mayweigh 1000 metric tons, while the VAWT 50 may weigh 20 metric tons.Preferably, the floating platform 220 is composed of laminated orreinforced concrete and can be constructed using conventional techniquesfor making floating platforms in the offshore oil and gas industry orthe like. Constructed in this manner, the platform 220 can have aconcrete shell enclosing air, expanded polystyrene, or other ballastmedium inside, and the shell can contain a number of inner chambers ordivisions.

Constructed in the above manner, the platform 220 can be a heavyfloating surface barge made of low-cost materials, such as reinforcedconcrete with floatation tanks. The floating surface barge 220preferably has its center of buoyancy higher above its center of gravityby a distance D so the barge 220 may be stable in high waves. Tominimize the tilting of the VAWT 50 having a height H at its maximumdiameter by a wind force F, the weight W of the barge 220 is preferablyheavy enough so that W×D is much greater than F×H. In addition, thefloating barge 220 can have extended horizontal reach to increase itsstability, as well as to provide a base for fastening the guy-cables 216of the VAWT 50 as shown in FIG. 4A. To minimize the materials required,the low-cost barge 220 can be of cross-shape or of star-shape with 3 ormore arms, as shown in FIG. 4A. The low-cost, heavy floating barge 220can also be used to support HADT or HAWT (not shown) with or withoutguy-cables.

Each end of the platform's arms 222 includes a pair of pulley systems250, and a number of anchor cables 230 pass through openings 224 in theends of the platform's arms 222 and through these pulley systems 250. Asshown in FIG. 4B, first ends of these anchor cables 230 connect to anunderwater weight 240 supported below the platform 220 and the surfaceof the water when deployed. This weight 240 can be composed ofreinforced concrete and can way about 300-500 tons. The opposite ends ofthe anchor cables 230 connect to a portable anchor 270 that rests on theseabed when deployed. Dual arrangements of these pulley systems 250 andcables 230 are used on each of the platform's arm 222 for redundancypurposes, but other implementations could uses a single pulley system250 on each arm 222.

As shown, the anchor 270 can have a triangular shape that mirrors thethree arms of the platform 200, although this may not be strictlynecessary. In particular, the anchor 270 has three feet 272interconnected to one another by cross beams 276. The feet 272 haveconnectors 273 on top for coupling to the anchor cables 230 and havecleats 274 on the bottom surface for engaging the seabed when positionedunder water. These feet 272 may have hollows 280 allowing the anchor 270to float when being towed. Although several techniques can be used todeploy the platform 220, weight 240, and anchor 270 offshore (asdisclosed in more detail below), operation of the anchor 270 and weight240 once deployed allow the platform 220 to move up and down relative tothe seabed, as also discussed in more detail later. This ability permitsthe platform 220 to passively adjust to changes in sea level due totides or storm swells.

C. Pulley Systems for Platforms

FIGS. 5A-5B show respective top-down and cross-sectional views of theends of the flotation platform's arms 222, revealing further details ofthe pulley systems 250. Each of these pulley systems 250 has a firstpulley 252 mounted on the platform 220 adjacent the opening 224 for acable 230. Coming from the submerged weight (240; FIG. 4B), the cable230 passes through the opening 224 and over this first pulley 252 to adirecting funnel 254. The funnel 254 directs the cable 230 to a secondpulley 258, and the cable 230 passes over this second pulley 258 to thesubmerged anchor (270; FIG. 4B) on the seabed below. This second pulley258 is mounted on a head 256 rotatably connected to the directing funnel254 so the second pulley 258 can pivot relative to the directing funnel254. In this way, the cable 230 can remain on the pulleys 252/258 whilethe second pulley 258 rotates during any tilting of the platform 220 inthe water.

Construction of portion of the platform 220 is also shown in FIG. 5B. Inparticular, the platform 220 as shown has an outer shell 221 composed oflaminated or reinforced concrete and has an inner chamber 223. Thepulley systems 250 are supported on a toe extending from this shell 221.The shell's inner chamber 223 can be filled with air, expandedpolystyrene, or any suitable ballast medium and can have dividedchambers or other divisions therein.

D. Third Embodiment of Floating Wind Turbine Having Four Arms, Weight,and Anchor

A third embodiment of an offshore wind turbine 300 shown in FIGS. 6A-6Bis similar to the offshore wind turbine 200 of FIGS. 4A-4B so that likereference numerals are used for similar components. Again, this offshorewind turbine 300 may be suitable for deployment in water having a depthof about 10 m to 50 m and can be deployed in a similar manner to theoffshore wind turbine 200 of FIGS. 4A-4B. In this embodiment of theoffshore wind turbine 300, the platform 220 has four arms 222 as opposedto only three. Having four arms 222 with each having dual guy cables,the turbine 300 may be better able to handle inclement weather such ashurricanes or typhoons. As shown in FIG. 6B, the portable anchor 270used with this offshore wind turbine 300 preferably has four feet 272 ina square pattern interconnected by various cross beams 276 to mirror theshape of the platform 220. These feet 272 may also have hollows 280allowing the anchor 270 to float when being towed.

E. Fourth Embodiment of Floating Wind Turbine for Shallow Waters NearShore

A fourth embodiment of an offshore wind turbine 400 illustrated in FIG.7A is suitable for deployment in shallow waters of a depth up to 15meters that may exist near a shore line. Again, this offshore windturbine 400 has a VAWT 50 with a rotor 52, curved blades 54, and otherconventional components. The rotor 52 mounts on a short stand 410 thatcan house some of the conventional components, and guy cables 216stabilize the rotor 52 to the platform.

The short stand 410 in turn rests on a submersible floating platform 420intended to rest on the seabed in shallower waters near shore. Thisplatform 420 has a central member 430 supporting the stand 410 and VAWT50 and has a plurality of toes 440 interconnected to the central member430 by cross beams 422. The platform 420 is preferably composed ofreinforced concrete and has a weight much greater than therelatively-lightweight VAWT 50. The platform's toes 440 have cleats 442on their bottoms for engaging the seabed and have turrets 444 on theirtops for connecting to the guy cables 216.

Although shown with guy cables 216 extending from the platform's toes440 in FIG. 7A, the guy cables 216 extending from the VAWT's rotor 52can be connected to the seabed as shown in FIG. 7B using pipe anchors460 or the like. When the wind turbine 400 is deployed, a temporarybracket and support bars are preferably used to support the rotor 52 tothe platform 420 because the guy cables 216 will not yet be installed.Once the platform is submerged to the seabed, the temporary bracket andsupport bars can be removed, and the guy cables 216 and pipe anchors 460can be installed to support the rotor 52. When two such wind turbines400 are deployed adjacent one another on the seabed, the adjacent VAWTs50 on the adjacent platforms 420 may share one or more the pipe anchors460 to support their rotors 52.

Although shown with the VAWT 50, the wind turbine 400 can alternativelyhave a horizontal axis wind turbine (HAWT) 40 as shown in FIG. 7C or adownwind horizontal axis wind turbines (HADT) 45 mounted on the platform420. Both the HADT 40 and HAWT 45 can have a rotor 42, blades 44, andtower 46 and can be supported on the floating platform 420 with orwithout guy cables (not shown). If guy cables are used, they can connectthe tower 46 to the platform 420 or to the seabed.

As shown in FIGS. 8A-8B, the offshore wind turbine 400 can beconstructed in stages on the beach near the shore line 42. In stages A,B, and C, for example, assemblers construct the submersible platform420, tower 410, rotor 52, and blades 54 as the assembly is pushed towardthe shoreline 42 along rails, rollers, or the like 46. As stage D, theturbine 400 is pushed into the water and floated to its shallowlocation. Finally, at stage E, the submersible platform 420 can be sunkin the water to rest on the seabed 40 so the rotor 52 and blades 54 canextend from the water to catch the wind.

To float the submersible platform 420 on the water in stage D, temporaryfloatation devices (not shown), such as buoys and cables, can be coupledto the submersible platform 420 to float it to a desired location nearshore, where the submersible platform 420 can then be lowered to theseabed 40. Alternatively, the submersible platform 420 can includehollows inside that allow it to float.

As shown in FIG. 7A, for example, each toe 440 and the central member430 can define hollows 450. These hollows 450 can be lined tanks withone or more valves 452. Regardless, these internal hollows 450 filledwith air allow the offshore wind turbine 400 to float on the water so itcan be towed to and from a site near the shore. When the hollows 450 arefilled with water, however, the offshore wind turbine 400 sinks in theshallow water, and the cleats 442 on the toes 440 engage the seabedwhile the rotor 52 and blades 54 extend vertically from the water, asultimately shown in stage E of FIGS. 8A-8B.

As shown in FIG. 8C, the wind turbine 400A may be deployed on arelatively flat area of seabed 40 so that the platform 420A can restlevel and the rotor 52 extend vertically from the water. Because theseabed 40 may not be perfectly flat and horizontal in the desiredlocation, the offshore wind turbine can be modified for the particularlocation where it is to be used so the rotor 52 will extend verticallyfrom the water's surface. As shown by the wind turbine 400B, forexample, the submersible platform 420B can be constructed with one ormore of its toes 440B angled off plane from the other toes so that thesubmersible platform 420B can be mounted at a predetermined orientationon the unlevel seabed 40 so the rotor 52 can extend vertically.

As shown by the wind turbine 400C in FIG. 8C, operators can use surveysof the seabed 40 in the desire location and can construct the rotor 52and/or stand 410 with a tilt at a designated angle so that rotor 52 willextend vertically from the water's surface when the submersible platform420B rests on the unlevel seabed 40. Alternatively, the connectionbetween the rotor 52 to the stand 410 or the stand 410 to thesubmersible platform 420C can be adjustable with a hinge mechanism orthe like (not shown) so that the rotor 52 can be corrected (tilted) toextend vertically should the offshore wind turbine 400 be deployed on anunlevel seabed that is less than ideally horizontal and flat.

Although the offshore wind turbine 400 is illustrated in connection witha VAWT 50, its more rigorous construction, and use of a non-floatingsubmersible platform 420, allows this design to be modified to include ahorizontal axis wind turbine (e.g., a HAWT) as well. However, use of aHAWT in the turbine 400 of FIGS. 7 and 8A-8C is not shown forsimplicity.

F. Fifth Embodiment Having Extendable Toes and Other Features

A fifth embodiment of an offshore wind turbine 500 is illustrated inFIGS. 9A-9B. As with previous embodiments, the offshore wind turbine 500has a VAWT 50 with a rotor 52, curved blades 54, a gearbox (not shown),an electric generator (not shown), and other conventional components.The offshore wind turbine 500 also has a floating platform 520 with fourarms 522 intended to float on the surface during normal operation tosupport the rotor 52 vertically above the water. As shown, a short tower510 supports the rotor 52 on the platform 520, and a plurality of guycables 516 connect the distal end of the rotor 52 to edges of theplatform 520 to provide extra stability for the rotor 52.

For additional stability, extendable toes 524 on ends of the arms 522can carry floatation elements 526 to further increase the platform'sexpanse on the surface of the water and to further increase theplatform's stability and buoyancy. These toes 524 and floatationelements 526 can be extended using motors after the offshore windturbine 500 has been moved to a desired offshore location and is readyfor operation.

G. Sixth Embodiment of Floating Wind Turbine Having Reclinable VAWT

The offshore wind turbines (e.g., 100, 200, 300, 400, and 500) of thepresent disclosure can have VAWTs 50 that are rigidly supported on theturbine's platform to always extend vertically therefrom. Alternatively,the VAWT 50 may be designed to recline on the platform, which can helpwhen towing the offshore wind turbine or to protect the VAWT 50 duringhigh wind conditions.

For example, FIG. 10 shows an offshore wind turbine 600 having a VAWT 50capable of being reclined and raised on the turbine's platform 620. Ahinged coupling 612 at one edge of the tower or stand 610 and areleasable coupling 614 at an opposite edge couple the VAWT 50 to theplatform 620. When transporting the offshore wind turbine 600 or whenstrong winds occur, the tower 610 can be decoupled at coupling 614 andpivoted (tilted) about the hinged coupling 612 to recline the VAWT'srotor 52 and blades 54 on the platform 620. Similarly, raising theVAWT's rotor 52 and blades 54 involves pivoting (tilting) the rotor 52about hinged coupling 612 and recoupling the tower 610 at coupling 614to secure the rotor 52 in its vertical position on the platform 620.

Reclining and raising the VAWT 50 on the platform 620 can be donemanually or can be performed remotely and automatically. For example,either temporary or permanent winches 628 on the platform 620 canrecline the VAWT 50 before an approaching storm. Operators can mountsuch temporary winches 628 on the platform 620, lower the VAWT 50, andmove the temporary winches 628 to another offshore wind turbine.Alternatively, remote transmissions from shore or a nearby vessel canactuate the releasable coupling 614 and can operate winches 628permanently mounted on the platform 620 (or on extendable toes).

In either case, the winches 628 when operated use the guy cables 616 topivot the rotor 52 on the hinged coupling 612 to either raise or lowerthe VAWT 50. For example, the VAWT 50 can be lowered to lay flat on thefloating platform 620 by adjusting the length of two opposite sets ofdual guy-cables 616 with the remotely controlled winches 628, while theother two sets of opposite dual guy-cables (not shown) remain taught. Inthis way, if storm winds occur in the area of the offshore wind turbine600, operators can remotely recline the VAWT 50 to prevent damage andminimize the impact of the strong wind and waves on the VAWT 50. Afterthe strong winds have passed, operators can then raise the VAWT 50. Thewinches 628 used can be mounted directly on the platform 620 or can bemounted on extensions 624 that are extend from the platform 620.

H. Modular Platform Construction

As discussed previously, the platforms used with the various embodimentsof the offshore wind turbines (e.g., 100, 200, 300, 400, and 500)disclosed herein can be composed of any suitable material, such aslaminated or reinforced concrete, and can be composed as a shell filedwith air or ballast material. In addition, the disclosed platforms, suchas platforms 220 of FIGS. 4A and 6A, can be constructed as one unit orone piece. Alternatively, the disclosed platforms can have a modularconstruction.

As shown in FIG. 11, for example, a modularly constructed platform 720has a plurality of interconnected floatation elements 730 attachedtogether in a desired arrangement, which in this example is a three-armshape. A central flotation element 740 is shown at the center of thethree arms for supporting the VAWT (not shown). The platform 720'smodular construction using the flotation elements 730 makes themanufacture and assembly of the platform 720 inexpensive and relativelyeasy. These floatation elements 730 can be composed of any suitablematerial and can have a hollow or solid construction as disclosedherein. In FIG. 12, for example, the floatation elements 730 have aconcrete shell 732 filled with a core 734 composed of expandedpolystyrene or other ballast material. These filled shells 732 can bebolted, tied, or otherwise fastened together end-to-end and side-to-sideusing connectors 736, such as bolts, cables, rods, etc., eitherinstalled internally as shown or applied on their surfaces.

I. Deployment and Assembly of Floating Wind Turbine

Details for assembling and deploying the shallow water offshore windturbine 400 of FIG. 7A have been discussed previously with reference toFIGS. 8A-8C. The VAWTs 200 and 300 of FIGS. 4A-4B and 6A-6B havingplatforms 220 and anchors 270 require different assembly and deploymentsteps—some of which are shown in FIGS. 13A-13C. In these exemplarysteps, the offshore wind turbine being assembled is the three-armedoffshore wind turbine 200 of FIGS. 4A-4B, although the same steps mayapply to the four-armed offshore wind turbine 400 of the FIGS. 6A-6B.Assembly of the turbine 200 can be performed right on the beach 42 asshown in FIG. 13B, or the assembly can be performed on a dock 44 with aramp extending into the water, as shown in FIG. 13C.

In a first assembly stage A, assemblers construct the platform 220 andanchor 270 adjacent one another. Moving the assemblies along rails,rollers, or the like 46 towards the shoreline 42, assemblers then addthe stand 210 to the platform 220 and install the rotor 52, blades 54,and other components of the VAWT 50 as the assemblies are moved closerto the shoreline in stages B, C, and D.

At stage E, assemblers float the anchor 270 and the platform 220 in thewater. As noted previously, the platform 220 is intended to float in thewater, while the anchor 270 when deployed is intended to rest on theseabed 40. To float the anchor 270, temporary floatation devices (notshown), such as buoys, coupled to the anchor 270 can be used.Alternatively, as shown in FIG. 4B, the anchor 270 can include hollows280 in its feet 272 that allow the anchor 270 to float. These hollows280 can be lined tanks with one or more valves (not shown) that can beflooded or evacuated to allow the anchor to sink or float.Alternatively, these hollows 280 can simply be open bottoms in the feet272 that can trap air allowing the anchor 270 to float and that can beflooded with water allowing the anchor 270 to sink. In either case, theanchor 270 can float on the water and be sunk to the seabed 40 wheredesired. These and other possibilities can be used. At stage F,assemblers then deploy the anchor 270 to the seabed 40 at a deploymentsite.

Several techniques can be used to tow the platform 220 and anchor 270 tothe deployment site where the anchor 270 can be lowered to the seabed40. In a first technique, the platform 220 and anchor 270 are floatednext to one another on the surface of the water and towed together tothe deployment site. Assemblers then sink the anchor 270 to the seabed40 by filling the hollows 280 in its feet. Specifically, assemblersflood one foot 272 of the anchor 270 so that it touches the seabed 40,and then complete flooding of the other feet 272 so that the anchor 270rests on the seabed 40. In sinking the anchor 270, assemblers attachfloats to the cables 230 connected to the anchor 270 so the cables 230can be retrieved at the water's surface. With the anchor 270 resting onthe seabed 40, assemblers float the platform 220 over the submergedanchor 270, retrieve the floated cables 230, pass the cables 230 fromthe anchor 270 through the pulley systems 250, and connect the cables230 to the weight 240. Finally, assemblers submerge the weight 240 belowthe platform 220 to tighten the cables 230 and finish the installation.

In a second technique, the anchor 270 can first be stacked below theplatform 220 on land or in shallow water, and then the stacked anchor270/platform 220 can be towed together to the deployment site on thewater's surface. At the deployment site, assembler can reeve cables 230to the anchor 270 from the platform 220 while lowering the anchor 270 tothe seabed 40 with winches (not shown). This process may require anumber of steps of sheaving, slacking, and tying off the cables 230 instages around the platform 220. After placing stops on the cables 230,assemblers can connect the cables 230 on the winch to the weight 240 andlower the weight 240 under the platform 270 to take up the slack in thecables 230. Assemblers may finally release the stops and completelowering the weight 240 below the platform 220 to complete theinstallation. With the offshore wind turbine 200 deployed, assemblerscan then take the winches to another platform to repeat the deploymentsteps on another assembly.

Should the wind turbine 200 need repair, operators can use winches tobring the weight 240 up from below the platform 220, detach the cables230 from the weight 240 and the pulley systems 250, and attach floats tothe cables 230 so the anchor 270 can be relocated later. The detachedplatform 220 can then be towed to shore for repair. If the anchor 270needs to be retrieved as well, operators can lift the anchor 270 fromthe seabed 40 with winches and then tow the combined platform 220 andanchor 270 to shore. Also, the hollows 280 in the anchor 270 can befilled with air to allow it to float as well.

J. Passively Adjustable Anchoring Systems

The offshore wind turbines 200 and 300 of FIGS. 4A-4B and 6A-6B haveanchoring systems (i.e., cables 230, weights 240, pulley systems 250,and anchors 270) capable of passively adjusting to changes in sea leveldue to tidal variations or storm swells. Details of this passiveadjustment are shown in FIGS. 14A-14D, in which the offshore windturbine 300 of FIGS. 6A-6B is shown adjusting to the changes in sealevel. When the sea level rises (FIGS. 14A to 14C) or lowers (FIGS. 14Cto 14A), the platform 220 raises and lowers accordingly on the surfaceof the water while remaining anchored by the cables 230, weight 240,pulley systems 250, and anchor 270. Should a significantly large swelldevelop during a storm, the platform 220 lifts to the full extent of theanchor cables 230 as shown in FIG. 14C. If the sea level increases evenfurther as shown in FIG. 14D, the sea level may even surpass theplatform 220 and the VAWT's rotor 52 and blades 54, which would thenremain at least partially submerged below the water level for protectionduring the storm or tidal wave.

In addition to the above anchoring system, the various embodiments ofoffshore wind turbines disclosed herein can use other passivelyadjustable anchoring systems, such as shown in FIGS. 15A-15C. Theadjustable anchoring system 840A of FIG. 15A uses a plurality of pulleys846 on the platform 820. Multiple anchor cables 844 pass through thesepulleys 846 and interconnect separate weights 842 to separate anchors848 in the seabed. It will be appreciated that the platform 820 may haveseveral such anchoring systems 840A connected symmetrically around theplatform 820 to anchor it to the seabed 40.

Another passively adjustable anchoring system 840B in FIG. 15B uses acommon weight 843 with the multiple anchor cables 844, pulleys 846, andanchors 848. The passively adjustable anchoring system 840C in FIG. 15Clikewise uses a common weight 843, but uses a single anchor cable 845that passes through a pulley 847 on the weight 843 as well as throughpulleys 846 on the platform 820. With the benefit of the presentdisclosure, it will be appreciated that other arrangements of weights,cables, pulleys, and anchors can be used to anchor the platforms 820.

K. Actively Adjustable Anchoring Systems

The various anchoring systems discussed previously act passively toraise or lower the platform with changes in the sea level. In additionalembodiments, the floating wind turbines of the present disclosure canuse actively adjustable anchoring systems capable of temporarily drawingthe offshore wind turbine under the water's surface for protectionduring harsh weather conditions.

In FIGS. 16A-16B, for example, an actively adjustable anchoring system840D has one or more mechanical winches 841 on the platform 820 that arecoupled to anchor cables 846 anchored to the seabed 40 with anchors 848.These winches 841 can be operated to either raise or lower the offshorewind turbine 800 relative to the sea level using the anchor cables 846.In this way, the operated winches 841 can shorten the length of thecables 846 to pull the offshore wind turbine 800 below the water'ssurface when strong winds or high waves occur (FIG. 16B), and can thenrelease the cables to allow the offshore wind turbine 800 to float at ornear the surface after the winds or waves have passed (FIG. 16A).Although this winching system is shown used with the platform 820intended to float on the water's surface and used with fixed anchors848, the winching system could also be used with any of the variousplatforms and anchors disclosed herein, even though such alternativesare not illustrated.

The VAWT 50 can remain fixed in the vertical position on the platform820 while drawn under the water's surface. Alternatively, as shown inFIG. 16B, the VAWT 50 can be reclined on the platform 820, as wasillustrated in FIG. 10. With this arrangement, the VAWT 50 could bereclined on the platform 820 as high winds develop, and the entireoffshore wind turbine 800 and platform 820 can be winched below thesurface as shown in FIG. 16B for protection. By reclining the VAWT 50,the amount of winching needed to pull the offshore wind turbine 800below the water's surface can be reduced.

L. Matrices of VAWTs

In a typical implementation, a large number of the disclosed windturbines may be used in a wind farm matrix at an offshore location. Thewind turbines can be anchored near one another and interconnectedtogether by common electrical cables. In a first example, FIGS. 17A-17Bshows just a portion of a wind farm matrix 900 having one arrangementfor interconnecting multiple wind turbines. In this example, the matrix900 uses the floating wind turbines 200 of FIGS. 4A-4B but couldlikewise use any other wind turbines disclosed herein, such as thenon-floating wind turbines of FIG. 7A-7D. In one implementation of thematrix 900, for example, each offshore wind turbine 200 can have a VAWT50 with a 300-kW capacity that converts the wind at sea to electricityat low cost. In a strong wind region offshore with annual mean windvelocity of 9 meters per second, for example, each offshore wind turbine200 may generate 1.0 million kWh of electricity per year.

In the matrix 900, power lines 952 connect the wind turbines 200 topower barges 950. In turn, these power barges 950 can connect to oneanother by power cables 954 as best shown in FIG. 17B. The power barges950 receive power (i.e., current) from at least some of the floatingwind turbines 200 to which they are connected, and communicate suchpower to a land-based station 956 or other power sink by one or morecommonly shared cables 954.

To install the matrix 900 offshore, each offshore wind turbine 200 canbe assembled, towed, and anchored into position using any of the methodspreviously discussed, and connected to the power grid (e.g., powerbarges 950) to generate electricity. Similarly, each offshore windturbine 200 can be easily disconnected from the matrix 900 and towedback to the shore for repairs and maintenance without affecting theentirety of the matrix 900. In this regard, it can be of substantialbenefit to use anchoring systems and methods that do not rigidly affixthe offshore wind turbines 200 to the seabed. For example, in each ofthe embodiments of FIGS. 4, 6, and 7, anchoring systems are used thatmerely rest on the seabed 40, which allow these anchoring systems to befloated to allow for easy installation or removal of a particularoffshore wind turbine from the matrix 900.

The power barges 950, like the platforms of the floating wind turbines,may float at or near the water's surface, and may be similarlyconstructed to the platforms of the floating wind turbines 200. Becausethe power barges 950 merely act as an electrical hub to which thefloating wind turbines 200 can connect and need not carry significanthardware beyond conventional connectors and cabling (unlike the turbines200), the barges 950 may not need to be anchored to the seabed 40 withthe same degree of diligence as do the turbines 200. For example, and asshown in FIG. 17A, a barge 950 may only use a single cable 951 andanchor 948 that may not be capable of either passive or active adjustingthe relative depth of the power barge 950. In another implementation, abarge 950 may not be anchored at all, and instead may rely merely on thepower cables 952 to keep the barges 950 into proper position relative tothe anchored floating wind turbines 200, assuming that suitably robustconnectors (not shown) couple the power cables 952 to the power barges950. In any event, the barges 950 may lack an anchor, have their ownanchors, connect by cables to the anchors of the offshore wind turbines200, or use any of the various anchoring systems disclosed herein.

In another arrangement shown in FIG. 18, the matrix 900 can connect to anearby offshore platform 970 to communicate power to the platform 970 orsome other power sink. For example, the offshore platform 970, ifinvolved in oil exploration, may contain a desalination system 960 usedfor injecting fresh water down a borehole of an offshore platform (notshown). On the platform 970, the desalination system 960 can use theprocess of reverse osmosis to produce fresh water from seawater so thefreshwater can then be used for filling, fracing, or other platformoperations. Because the desalination system 960 can require a great dealof energy to operate, using the wind farm matrix 900 near thedesalination system 960 to provide the power can greatly facilitateoffshore drilling operations.

The foregoing description of preferred and other embodiments is notintended to limit or restrict the scope or applicability of theinventive concepts conceived of by the Applicants. With the benefit ofthe present disclosure, it will be appreciated that details describedwith respect to one embodiment disclosed herein can be combined with orused on other embodiments disclosed herein, even though such combinationor use may not be explicitly shown or recited herein. In exchange fordisclosing the inventive concepts contained herein, the Applicantsdesire all patent rights afforded by the appended claims. Therefore, itis intended that the appended claims include all modifications andalterations to the full extent that they come within the scope of thefollowing claims or the equivalents thereof.

1. A method for deploying a wind turbine, comprising: floating an offshore wind turbine to a desired position offshore, the offshore wind turbine comprising— a vertical axis wind turbine comprising a vertically-extending rotor, a plurality of blades coupled to the rotor, and a generator for producing power from rotation of the rotor, a floating platform upon which the vertical axis wind turbine is mounted, wherein the floating platform floats in water to support the vertical axis wind turbine above the water surface, and an anchoring system coupleable to the floating platform, the anchoring system having an anchor and a weight connected by a cable; anchoring the floating platform to the seabed with the anchoring system by resting the anchor on the seabed; and supporting the weight between the floating platform and the anchor by passing the cable through at least one pulley on the floating platform.
 2. The method of claim 1, wherein anchoring the floating platform to the seabed comprises resting the anchor on the seabed without directly affixing the anchor to the seabed.
 3. The method of claim 1, wherein anchoring the floating platform to the seabed comprises flooding the anchor.
 4. The method of claim 1, wherein the anchoring system allows the floating platform to be passively or actively adjusted to maintain a proper position relative to the water surface.
 5. The method of claim 1, wherein floating the offshore wind turbine to a desired position offshore comprises floating both the floating platform and the anchoring system as separate pieces or as a stack.
 6. The method of claim 1, further comprising floating the offshore wind turbine from the desired position offshore to a position on shore.
 7. The method of claim 6, wherein floating the offshore wind turbine from the desired position offshore to a position on shore comprises floating the anchoring system.
 8. The method of claim 1, wherein a plurality of the cables connect the weight to the anchor, and wherein supporting the weight comprises passing the cables through a plurality of the at least one pulley disposed on the floating platform.
 9. The method of claim 1, wherein the floating platform comprises a plurality of legs spreading horizontally from the vertical axis wind turbine.
 10. The method of claim 1, wherein the vertical axis wind turbine is tiltable with respect to the floating platform.
 11. A method for deploying a wind turbine, comprising: floating an offshore wind turbine to a desired position offshore, the offshore wind turbine comprising— a vertical axis wind turbine comprising a vertically-extending rotor, a plurality of blades coupled to the rotor, and a generator for producing power from rotation of the rotor, and a submersible platform upon which the vertical axis wind turbine is mounted; and sinking the submersible platform to come to rest on the seabed, wherein the submersible platform is not directly affixed to the seabed, and wherein at least a portion of the vertical axis wind turbine remains above the water surface.
 12. The method of claim 11, wherein the submersible platform comprises a plurality of legs spreading horizontally from the vertical axis wind turbine.
 13. The method of claim 11, wherein the submersible platform comprises hollows, and wherein sinking the submersible platform comprises filling the hollows with water.
 14. The method of claim 11, further comprising adjusting an axis of the vertically-extending rotor relative to the sunk submersible platform, wherein the adjusted axis is generally vertical.
 15. The method of claim 11, further comprising adjusting an angle of the submersible platform relative to the seabed so that the submersible platform is generally horizontal.
 16. The method of claim 11, further comprising floating the submersible platform to move the offshore wind turbine from the desired position offshore to a position on shore.
 17. The method of claim 11, wherein sinking the submersible platform to come to rest on the seabed comprises: sinking a rigid body of the submersible platform on which the vertically-extending rotor is perpendicularly mounted, and resting a preconfigured angle defined by the rigid body on the seabed such that the vertically-extending rotor extends generally vertical from the water surface.
 18. The method of claim 11, further comprising: supporting a proximal end of the vertically-extending rotor on the submersible platform; and securing a distal end of the vertically-extending rotor by cables directly to the seabed or to the submersible platform.
 19. A method for retrieving a movable wind turbine, comprising: raising an offshore wind turbine from the seabed to float in the water, the offshore wind turbine comprising— a vertical axis wind turbine comprising a vertically-extending rotor, a plurality of blades coupled to the rotor, and a generator for producing power from rotation of the rotor, and a submersible platform upon which the vertical axis wind turbine is mounted; and towing the floating offshore wind turbine to shore.
 20. A method for deploying a wind turbine, comprising: assembling an offshore wind turbine on shore, the offshore wind turbine having a vertical axis wind turbine mounted on a submersible platform; floating the assembled offshore wind turbine to a desired position offshore; submerging the submersible platform to the seabed while the vertical axis wind turbine extends above the surface of the water; and connecting the vertical axis wind turbine to a power cable.
 21. A method for retrieving a movable wind turbine, comprising: disconnecting an offshore wind turbine from a power sink, the offshore wind turbine having a vertical axis wind turbine extending above the surface of the water and having a submersible platform submerged to the seabed; raising the submersible platform from the seabed to float in the water; and towing the floating offshore wind turbine to shore. 